Self-propelling projectile



April 12, 1938.

L. DAMBLANC SELF PROPELLING PROJECTILE Filed March 5, 1956 LOUIS DAMBLANC PUTGENEYS Patented Apr. 12, 1.938

SELF-PROPELLING PROJECTILE Louis Damblanc, Paris, France Application March 5, issaserial No. 67,403

In Belgium March 9, 1935 r 7 Claims.

The present invention relates to self-propelling projectiles,.that is to say projectiles which are l provided, in addition to their specic charge,

which may be of any nature whatever (for start- 5 ing a re, producing a smoke of a special kind, etc.), with a propelling charge the combustion Vof which imparts to said projectiles, along at least a portion of their path of travel, a certain impulse. The invention is more especially, al- 10 though not exclusively, concerned, among projectiles of this kind, with rockets.

The object of the present invention is to providea projectile of the kind above referred to which is better adapted to meet the requirements of practice, and in which, in particular, the combustion of the propelling charge contained in the projectile isutilized with an improved efficiency.

The essential feature of the present invention consists in devising the envelope of a projectile of the type above referred to in such manner that the length of said envelope is gradually reduced as the propelling charge is being gradually burnt. Other features of the present invention will result from the following detailed description of 25 some specific embodiments thereof. l

Preferred embodiments of the present invenftion will be hereinafter' described, with reference to the accompanying drawing, given merely by way -of example, and in which:

30. Fig. 1 is anelevatlonal view, partly in section, of a rocket made according to an embodiment of the present invention;

Figs. 2 and 3 are views, similar to Fig. 1, relating to other embodiments.

3'5 r'Ihe examples that will be hereinafter describedconcern the case of rockets in which the propelling charge lis divided into a plurality of stages of combustion.

Concerning, the general arrangement, with the 40 exception of the envelope containing the propelling charges, it is devised in any usual manner known in the art.

Concerning the stages, or chambers, of combustion, (which are supposed to be four in number in the following description), they rare advantageously superposed inV the direction of the longitudinal axis of the rocket,.which is for instance given the general shape of a cylinder.

I further provide, in the direction of the axis of each chamber I, 2, 3, or 4, a nozzle 5, consisting of a cavity or recess, preferably of the shape of a frustum of a cone, the dimensions of which will be moreparticularly referred to in what follows, said nozzleubeing intended to facilitate the propagation of combustion in the charge..

(c1. 1oz-2c) vAdvantageously, the 4respective chambers i, 2, 3 and 4 are separated from one another by means of annular elements 6, made for instance of cardboard, which prevent premature ignition of the successive charges of -said chambers.

As for the charges, they may consist of any 4suitable matters, for instance powder. Y

Concerning now the envelope to be provided, in d such a rocket for forming thevarious chambers of combustion', instead of making it of a metal (or any other matter) capable of withstanding without deterioration the temperatures resulting from the combustion of the powder, according to the present invention it is made in a different manner, as will be hereinafter explained. As a matter of fact, the use of -a metal capable of withstanding the temperatures of combustion of the charge would have the following drawbacks:

(a) Formation of eddies in the free part of the envelope or cartridge as the charges of the ilrst chambers disappear by combustion;

(b) Heating of said free part, due to the fact that it is no longer heat insulated by the presence of powder thereon;

(c) Reduction of the useful outlet pressure; and

(dlDead weight constituted by the parts of the envelope that -are no longer useful.

According to the present invention, said envelope or cartridge is devised in such manner that its length is gradually reduced as the propelling charge that it contains is being burnt.

This result can be obtained in various ways. For instance, according to an embodiment of the invention, illustrated by Fig. 1, the cartridge or envelope is constituted by the mere juxtaposition of annular elements 1, of copper for instance, said elements being kept in position owing to the cohesion of the charge of powder they surround.v With this arrangement, as it will be readily understood, the combustion of the charge of powder produces the successive elimination of annular elements 1.

However, I considerthat it is more advantageous to constitute the cartridge or envelope of the assembly of elements, the number of which is, for instance, equa'lto the number of chambers or stages of combustion, established, or connected together, in such manner that each of the ,elementary propelling charges produces, at the end of its combustion, the elimination, through partial or total melting, or through combustion, of the element of the cartridge or envelope that contained said elementary charge.

In order to carry out a rocket according to this embodiment of the invention, it is necessary to make use of a metal, or other material, which melts at a temperature lower than the tempera` ture of combustion of powder (about 300 CJ, while being sufficiently strong for' constituting the cartridge or envelope of the rocket.

'I'here exist,I at the present time, many alloys l which comply withvthese conditions, for instance the following:

Rose's metal (1 part of tin, 1 of lead, 2 of bis- -muth) the melting point of which is 110;

Woods metal (4 parts of tin, 8 of lead, 15' of bismuth and 4 of cadmium), the melting point of which is 70 C.; and

Lipowitz metal (4 parts of tin, 2 of lead, 16

of bismuth and 3 of cadmium), the melting pointof which is`60 C.

According to the present invention, I may, fo

instance, provide annular parts separating the envelope into a plurality of elements, said annular separating parts being made of one of these metals.

` According to the embodiment illustrated by Fig. 2, the elements 8, 9, I0 and Il ofthe envelope are made of Woods metal.

These elements are connected with one another and with the nose l2 of the4 rocket throughan element containing still a certain amount of powder. Experiments proved, from this point of View, that it suffices, when nozzle 5 is axial and of the shape' of a frustum of a cone, to give it an apical angle of about 10.

It is further necessary to provide', between the end ofthe apex of each nozzle 5 and the corresponding ring 6, a thickness of powder sufficient in `order that the next element should not start burning before the first element, containing said nozzle 5, i-s wholly emptied of powder.

It will be readily understood that, with such an arrangement, oncecombustion of the powder lshall have been started, this combustion taking vbe made in various manners. ning to my invention, they should preferably conplace along concentric zones, the disengagement of heat produced by the combustion of the charge of chamber l for instance shall not act on element 8 as long as there remains upon the wall of said element a slight layer of powder' which constitutes a heat insulation, whereas, immediately after the combustion of this layer, said heat causes the element in question to melt.

of the invention, provide elements of the cartridge or envelope made of any metal, said elements consisting, as shown by Fig. 3, of four sleeves 8', 9', I0', Il' of copper,`or preferably of magnesium or of a light alloy oi.' this metal, said sleeves being connected with one another and with the nose of the rocket by annular elements made, at least partly, of Woods metal.

"Ihese elements made of Woods metal ,may

However, accordsist, as shown by Fig. 3, of rings I4 clamped to each of the two adjacent elements vto be assembled together.

Nozzle 5 must then be given a size .such that the particles of powder in contact with ring I4' given oiby the vvexhaust gases ensure a continuous or discontinuous elimination of these elements.

Finally, the projectile above described may further includel any suitable stabilizing device, such for instance as ribs or ns which are carried either by the elements intended to be eliminated, or by the portion of said projectile that is intended to remainas long as said projectile is moving along its path oi.'I travel.

The projectile above described avoids all the drawbacks above mentioned and it further presents many advantages, the chief of which are the following: v

It may include a number of combustion chambers as high as it is desired;

Furthermore, its construction is both simple and cheap..

A rocket according to the present invention may be combined with various devices, such, for

instance, as the following:

(a) Objects to be transported, for example the Y' end of a cable, or a message, introduced, for this purpose, in a recess provided in the head of the rocket: l

(b) Luminous signals: A

(c) Atmospheric or stratospheric sounding devices; and so on. H

Of' course, although the rocket shown by the drawing is of cylindrical shape, this is by no means a necessity, as the whole may of course be made of any desired shape.

Furthermore, the projectile might include not l. A rocket having a charge of powder divided into a plurality of parts, each of such parts having a recess therein, a casing surrounding said parts and formed of a plurality of metallic elements associated with the respective charge 'parts I may also, according to another embodiment.

some of which are fusible at the combustion temperature `of the powder forming the charge, said recesses being so located in each part of the charge that betweenveach recess and the associated fusible metallic element there is a layer of powder of sufcient thickness to prevent the melting of each fusible element until the part of the charge which corresponds thereto has been substantially completely burned.

2. A rocket having a. charge, of powder dividedr into a vplurality of parta-each of such parts having a recess therein, a casing surrounding said parts and formed of a plurality of metallic eleausgew o! the powder forming the charge. and iniusible rings joining said elements, said recesses being so located in each part-oi' the charge that between the recess and thewall of the fusible metallic element there is a layer of powder of suiicient thickness to prevent the melting of each fusible metallic element until the part of the charge ring there is a. layer of powder oi suicient thickness to prevent the melting of leach fusible ring until the part of the charge which is contained in the corresponding influsible section has been substantially completely burned.

4. A device as claimed in claim 3, in which said rings are formed of Woods metal.

5. A device as claimed in claim 3, vin which said infusible sections are formed of a light metal alloy.

6. A device as claimed in claim 3, in which said infusible sections are formed of magnesium.

7. In a device as claimed in claim 3, said recesses being so located that substantially all'the powder in each lsection burns before the burning of the powder in contact with the fusible rings. i

` IDUIS DAMBLANC. 

